Although atmospheric absorption and rain attenuation beyond the natural Friis free space loss at sub-THz and THz transmissions are greater than frequencies below 6 GHz (where air causes attenuation of only fractions of dB/km) [1]}, [2]}, work in [3]} shows that the atmospheric absorption has remarkably little impact on total path loss out to a few hundred meters and heavy rain will practically limit fixed THz links to several km. The atmospheric absorption at sea level in standard condition at 200-300 GHz is less than 10 dB/km, and even at 800-900 GHz the additional atmospheric absorption beyond the natural Friis free space loss is 100 dB/km at sea level, which is only 10 dB per 100 m over today’s 4G cellular, which will be compensated for by the antenna gains at higher frequencies [3]}.
